getSymbols（在R quantmod包中）不适用于FRED数据

Question

R的quantmod包中的library(quantmod) getSymbols('CPIAUCNS',src='FRED') 命令不再适用于FRED数据（即，对于圣路易斯联邦储备银行数据库，请通过：fred.stlouisfed.org）。例如，使用R中的quantmod帮助菜单提供了此示例，该示例不再有效：

Error: Failed to download file. Error message:
cannot open URL 
'https://fred.stlouisfed.org/series/CPIAUCNS/downloaddata/CPIAUCNS.csv'
If this is related to https, possible solutions are:
1. Explicitly pass method= via the getSymbols call (or via setDefaults)
2. Install downloader, which may be able to automagically determine a method
3. Set the download.file.method global option
In addition: Warning message:
In download.file(url, destfile, method, quiet, mode, cacheOK, extra) :
  cannot open URL 
'https://fred.stlouisfed.org/series/CPIAUCNS/downloaddata/CPIAUCNS.csv': 
HTTP status was '404 Not Found'

运行此命令会产生此错误：

getSymbols

显然，圣路易斯联邦储备银行改变了FRED代码的网页地址，并且对于新地址来说并不明显（至少对我而言）。您仍然可以手动将数据下载到Excel文件中。但是FRED的ref = db.getReference("/foo/{var}/bar"); 被打破了。有想法该怎么解决这个吗？谢谢！